This talk is based on a joint work with Nakao Hayashi and Pavel Naumkin [8]. We consider the initial value problem for the nonlinear Shrödinger equation of the derivative type:whereand u is a complex-valued unknown function. We will occasionally write u x for ∂ x u, and u denotes the complex conjugate of u. The nonlinear term N(u, u x ) is a cubic homogeneous polynomial in (u, u, u x , u x ) with complex coefficients, and it satisfies so-called gauge invariance, that is,The aim of this talk is to present a structural condition on the nonlinear term N under which the corresponding forward Cauchy problem (1) has a disspative nature. To explain the motivation, let us begin with the simplest case where N is independent of u x , i.e., N = λ|u| 2 u with λ ∈ C. Then it is easy to see thatwhich suggests dissipativity if Im λ < 0. In fact, it is proved in [17] that the solution decays like O((t log t)x as t → +∞ if Im λ < 0 and u 0 is small enough. Since the non-trivial free solution (i.e., the solution to (1) for N ≡ 0, u 0 = 0) only decays like O(t −1/2 ), this gain of additional logarithmic time decay reflects a disspative character. Now we turn our attentions to the general gauge-invariant cubic nonlinear terms involving both u and u x . Note that we can not expect the conservation law like (3)